Pollution control requirements have pushed allowable levels of contaminants such as Sulfur in fuels (coal, diesel, gasoline, etc.) to such low levels that they are becoming difficult to measure. One previous technique, X-ray Fluorescence Spectroscopy (XRF) is capable of measuring levels as low as 10 ppm in Diesel fuel but lower levels become difficult. This difficulty is the result of getting sufficient x-ray flux from the primary excitation beam onto the target, getting the desirable energy of x-rays onto the target, and getting sufficient characteristic x-rays out of the target and into a detector.
Accordingly, an X-ray fluorescence spectrometer may be thought of as having two main component elements: 1) an X-ray generator which may emit a broad spectrum of X-rays and 2) an X-ray detector, comprising one or more optics which gather the emitted X-rays, perhaps selects rays of a desired energy spectrum and directs them through a window leading to the detector. The presently disclosed invention first relates to the X-ray generator component of the spectrometer. The invention also relates to the detector portion of the spectrometer.
Moreover, in x-ray analysis it is often desirable to produce a small spot with a high flux of nearly mono-energetic x-rays. Most current systems are inefficient at this because they collect a very small portion of the emitted x-rays. The x-ray optical system disclosed here would collect a very large solid angle of the emitted x-rays, monochromatize them and then concentrate them to a small spot.
Additionally, in X-ray micro-analysis, Wavelength Dispersive Spectroscopy (WDS) is used whenever high energy resolution or high count rates are needed for the sample being analysed. Unfortunately, many WDS systems suffer from low count rates because the diffractor collects a small solid angle of the emitted x-rays. It is sometimes possible to move the diffractor closer to collect a larger solid angle but this causes poor resolution. Sometimes, special optics can be used to collect a large solid angle but previous optics have had small collection angles for energies above 1000 eV. The x-ray optical system disclosed could be used for a new type of WDS using the unusual x-ray optics that collect a large solid angle with high efficiency.